Effect of montelukast added to inhaled corticosteroids on fractional exhaled nitric oxide in asthmatic children. L. Ghiro, S. Zanconato, O. Rampon, V. Piovan, M. F. Pasquale, E. Baraldi. #ERS Journals Ltd 2002. ABSTRACT: The aim of this prospective, self-controlled, single-blind study was to assess the effect of montelukast added to maintenance therapy with inhaled corticosteroids (ICS) on fractional exhaled nitric oxide (FENO) in asthmatic children.Thirty-five children (age 11.2¡0.4 yrs (mean¡SEM)) with mild-to-moderate persistent asthma treated with low to medium doses of ICS and FENOw20 parts per billion (ppb) were included. The patients were randomly assigned to two groups: 17 patients continued ICS (group C) and 18 had montelukast added to ICS for 3 weeks (group M). FENO measurements were performed in both groups at baseline (T1) and after 3 weeks (T2), and in group M also after 2 weeks of washout. FENO was measured by a chemiluminescence analyser using an on-line method (50 mL?s -1 ) with nitric oxide-free air. The overall mean daily dose of ICS was equivalent to 530¡58 mg?day -1 of beclomethasone in group M and to 564¡55 mg?day -1 of beclomethasone in group C. There were no significant differences in baseline FENO and forced expiratory volume in one second (FEV1) between the two groups. After 3 weeks there was a significant reduction of FENO values in patients of group M (T1 52.2¡7.8 ppb, T2 36.1¡4.6 ppb) but no significant changes in group C (T1 43.5¡6.0 ppb, T2 47.8¡9.4 ppb). In group M after 2 weeks of montelukast withdrawal, FENO rose to baseline values (55.6¡8.7 ppb).In conclusion, after montelukast treatment there is a fractional exhaled nitric oxide reduction in asthmatic children receiving maintenance therapy with inhaled corticosteroids. This suggests an anti-inflammatory effect of montelukast additive to that of inhaled corticosteroids. Fractional exhaled nitric oxide (FENO) has been proposed as a simple and noninvasive marker of airway inflammation in asthmatic patients [1]. Several studies have demonstrated that FENO in asthmatics is reduced by corticosteroid therapy [1,2], and that changes in FENO due to steroid dose changes precede the improvement or worsening in asthma symptoms and lung function [1]. Recently FENO was demonstrated to be useful in predicting loss of control in asthmatic subjects when inhaled corticosteroids (ICS) were withdrawn [3], with a positive predictive value similar to that obtained using sputum eosinophils and airway hyperresponsiveness, but with the advantage that FENO is an easier-to-measure, real-time parameter. This evidence suggests that FENO measurement reflects control of asthma and may help the physician in modulating anti-inflammatory therapy [1].The cysteinyl leukotrienes (Cys-LT) C4 and E4 play a key role in the pathophysiology of asthma [4]. The leukotriene receptor antagonists (LTRAs) that have recently been developed selectively block the binding of Cys-LT to the CysLT1 receptor, which has been identified as the receptor through which most their actions...